> Script Details
Convex Hull / Convex Envelope
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Dr Michael Sawada
Apr 15 2002
Status of work
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This program presents an interface with a dropdown list of all point layers in the current DataFrame. Choose one and the program creates a polygon shapefile containing either:
1. the convex hull of a set of points or
2. the convex envelope (minimum bounding) of a set of points
The polygon shapefile is stored in the projection (coordinate system) of the DataFrame and is added to the currently active DataFrame as a new layer.
Options available are:
1. To construct convex polygon on currently selected subsets of points
2. To construct convex polygon on all points in layer.
3. To buffer (either positively or negatively) the convex hull or envelope within the units of the current Dataframe. This allows expansion or contraction of the minimum bounding convex polygon.
4. Rectangular convex envelopes can be expanded so that they remain square or buffered in the conventional sense.
1. A shapefile of name chull_LayerName.shp
2. An associated chull_LayerName.dbf file with area and perimeter of the convex polygon.
Written in Visual Basic for Applications (VBA) and requires ArcGIS 8.1. A single user form to be associated with a UIControlButton. This procedure is in the readme.pdf file within the zip archive.
NOTE: Multipoint layers are not supported in this version, in other words, there needs to be a single record for each point within the point layer.